1. Field of the Invention
The present invention relates to an impact modifier for a polymer composition. More particularly, the present invention relates to an impact modifier for a polycarbonate resin composition, which provides enhanced coloration and impact resistance.
2. Description of the Related Technology
Generally, a polycarbonate resin has excellent impact strength, self-extinguishment, dimension stability and heat resistance. Thus, a polycarbonate resin has been widely used as a housing material for various electronic or electric devices.
However, a polycarbonate resin has poor flowability due to its high melting point. Thus, the resin requires a high temperature for processing. Such a high processing temperature causes a resulting product to have deteriorated impact resistance. To avoid this problem, a polycarbonate resin is typically used in mixture with various impact modifiers.
Although impact modifiers improve the impact strength of a polycarbonate resin, such impact modifiers causes other problems. For instance, a butadiene rubber-based impact modifier commonly used in a polycarbonate resin tends to be degraded or scorched during a molding process of over 300° C. This problem causes deterioration of heat stability and weather resistance, thereby limiting application of the impact modifier. An acrylate rubber-based impact modifier generally provides good heat stability and weather resistance. However, it shows poor coloration property and impact resistance at a low temperature.